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Saturday, 30 May 2015

IN THE HEART OF THE MILKY WAY THERE IS A SPACE-TIME TUNNEL

The study suggests that the center of our galaxy, where he is "Sagittarius A *", a strong source of radio waves discovered in 1974, there is - as it was believed until now - a black hole "supermassive", with a mass of millions (or billions) of times higher than that of our small sun.In its place would be instead a "Wormhole" (which literally means "worm hole", as if he had dug a worm): a "wormhole" able to link two places and two different times of the same universe or even two different universes.Stuff of science fiction. Intrigued by the evocative topic, we hit the Chinese team leader of this research is the cosmologist Cosimo Bambi, a young Italian physicist who teaches and does research in Shanghai. We asked him a few questions. Professor Bambi, what it Stratta? There are really similar properties to the novel? First I would like to specify the content of the paper appeared recently on arXiv. Currently, it is believed that the center of each galaxy "normal" there is a supermassive black hole simply because, observing the rotation of nearby stars, it follows that there is an object with a very large mass in a relatively small volume. If the object at the center of our galaxy, not observed any possible heat radiation from its surface. These two considerations suggest that it is a black hole. But, in reality, do not rule out other possibilities.The term "wormhole" may indicate things slightly different character: in our work, I and my student, we assumed the existence of a "traversable wormhole", which is just a kind of wormhole: a structure non-trivial topology that works as a "shortcut" connecting two distant regions of the universe itself, or two different universes. In what sense is defined as "traversable"? You could go in for really? The wormhole is "traversable" because an observer can go from one side to another and then back again. These strange objects are not forbidden by the theory of general relativity and can be mistaken for holes blacks: they too can have a very large mass in a relatively small and certainly not emit heat radiation from their surface because they have no surface. In other words: the current observations can not distinguish whether the supermassive object at the center of our galaxy is a black hole or a wormhole. In our work we show that certain observations can do it. How did you come to that conclusion?How instrumentation and through what circumstances? The doctoral thesis of Zilong (the other author of the study, ed) concerns the possibility of using astronomical observations verify whether objects that currently are believed to be holes blacks of general relativity they are so.In particular: we are studying the properties of the radiation emitted by a blob of plasma that orbit close to one of these objects. Since the gravitational force around a black hole and a wormhole is different, the light rays are deflected in a different way. Doing the math, you see that the secondary image of a blob of plasma seen by a distant observer (the image formed by light rays that make a half turn around the object and then get the viewer away) is significantly different in the case of a black hole and a wormhole. In the case of the wormhole, the gravitational force is weaker and so the secondary image is on a smaller circumference on the image plane of the observer. These observations will be possible in a few years, for example with the instrument GRAVITY in Chile (a large observatory ESO, the main European intergovernmental organization that deals with astronomy, ed). Over the next 5-15 years, however, they will be developed new tools capable of going to see things that were not possible before, and so it makes sense to check if what we think is true is actually true. If you were right we would be faced with one of those "topos" which fed the imagination of science fiction writers. And that actually form a very impressive phenomenon ... What do you feel, that she is a scientist, the face of this possibility? My answer will seem strange, but an object like a wormhole is actually something far from reality only if you think about what we see around us. From a theoretical point of view it is not something so ... imaginative. And the conditions that are close to one of these objects at the center of galaxies are very far from the conditions on Earth. I do not say that I strongly believe in the existence of wormholes. I say that from a theoretical point of view is acceptable, but our theoretical knowledge on the subject are undoubtedly incomplete, so it is useful to see if we can learn something from observations. And in this case it seems that the answer is positive.Let's move on to a more personal key. "A Florentine in Shanghai" seems to be the beginning of a joke. But he talks to her, a young physicist, an Italian scientist who teaches and does research at Fudan University of Chinese megacities. It passed from Italy to the US, then to Germany and finally to China. How did we get there? And why? After his doctorate in Ferrara, researcher have been a year in Michigan, three years in Japan, and one year in Germany. Then I came to Shanghai, China. Clearly I had no problems to move. I think for what I'm concerned, the opportunity to do research here are really good for a person of my age. If I had 10-15 years more, I could find the same conditions in Germany or in Japan (in Japan but probably only if I was Japanese), not now. The US fascinate me a lot less, but I'm talking about my specific field of research. What "is irrelevant" in Italian academia not Italian? Which only the most glaring differences between the Italian and Chinese Academy? And what you can pick up different opportunities? I can answer this question regarding my field. Honestly I do not like the Italian academic system, because I find it difficult to do research. The opportunities at Fudan are really interesting. I'm 33 and I have a position that, in Italy, would correspond to that of Professor. If I have an idea here, I do my own project proposal and, if approved, have a research fund that I manage as I want (in Italy this is not possible because the proposals are made by groups of teachers and therefore no is truly independent and decision times inevitably are longer). Here I have the opportunity to really have a group working on my projects. I arrived a year and a half ago and in my group I have six students, each working on a particular aspect of one of these projects;then there are two senior researchers (in Italy, but also in the rest of Europe or the United States, would not be possible for a person of my age). In Italy it is not possible to form a group because the number of doctoral students within a Department of Physics is too low - most of the professors and graduate students did not, whereas the teaching load in Italy can be substantial, it is difficult find the time to do research without the help of students. How much time does the teaching, in his life to Shsnghai? Here at Fudan teach only a half-year course per year, so I really the time to devote to research. But China is not everywhere so it is true in Fudan, not least in the universities titrated. Fudan University is one of the most prestigious of the country is part of the "Ivy League" of China, the so-called "C9 League", the leading researchers of the Asian giant. A note geopolitics: now that China has overtaken the US in the world ranking of trading powers, when he believes (if ever) that can achieve the same levels of excellence in research? China is growing a lot, even in the field of research, but I think that in many areas the gap with Europe and the United States is still considerable. Then there is to say that here there is a small number of universities and research institutions (mainly in Beijing and Shanghai) who has money and is growing fast, but in the vast majority of university level is much lower. What school he attended, before enrolling at the Faculty of Physics? It was a "model student" or floated in the media? What subject she liked more, among those studies? Before you enroll in the faculty of physics at the high school I was Guido Castelnuovo di Firenze. In general, I was among the best students in my class: the best in mathematics and physics, but in other disciplines were classmates better than me. What's life like in Shanghai, a researcher for Italian? There is a community which is referred or are all true "globe-trotter", stateless necessity or fate? I moved to Shanghai about a year and a half ago, because the opportunity to do research are really good and then, not having started a family, it is easy for me to move and to choose only according to my needs. Shanghai is a very international city, so English is enough for me for the moment; I know just something in Chinese for emergencies or very simple things.Personally an international climate without national references too pronounced I do not mind. If, however, he wanted the Department of Physics at Fudan here we are all Chinese working on the physics of low energies, but three professors are Italian: besides me, Anthony Marciano and Leonardo Modesto. We work on gravity and cosmology. The air is really unbearable as is clear from the report on air pollution? Pollution is undoubtedly the main problem of Shanghai, because the rest of the city can offer a lot. The gap with other cities in China and is remarkable, especially in the interior regions, the country is still very backward. His first name is Cosimo, an explicit part of the "fiorentinitudine". Did he ever think, when you look, studying or looking at the stars, which is the same name that brought the protector of Galileo, Cosimo II de Medici?Gambling: homonyms this has played a role in his decisions? In fact, when I am asked the origin of my name - especially since no Italian who do not know that Cosimo is a name Florentine - joke that Cosimo and cosmology have the same origin (from the greek "cosmos", ordered) and that is That's why I deal with gravity.